I refer to the letter 'Work at reducing emissions' (South China Morning Post, November 21). As I set out in that letter, it is my understanding from tests undertaken abroad with liquefied petroleum gas (LPG) that LPG offers certain environmental advantages in the form of reduced emissions when an engine is idling. However, when the engine is under load, emissions of nitrogen, oxides, carbon monoxide and hydrocarbons are significantly higher than for petrol engines. I can only presume by their silence that Christine Loh, with whom I was in correspondence through your columns on this subject matter, and the Hong Kong Government Environmental Protection Department accept that my comments are correct. That being so, I must seriously question why it is that they and the Hong Kong Government seem to be set on forcing taxis to convert to LPG as this is unlikely to have any significant impact upon vehicle emissions in Hong Kong and indeed may well exacerbate the problem. F. A. WILSON Mid-Levels
